Thermodynamic modeling of sensitization of AISI 304 stainless steels containing nitrogen

Effect of nitrogen content in sensitised austenitic stainless steel on the crack growth rate in simulated BWR environment

“…6a and b however, the coverage of the chromium depleted regions is appreciably higher in SS 304 LN1 as compared to SS 304 LN2. Higher nitrogen level in SS 304 LN2 also results in higher chromium levels in the depleted regions [61]. In the SS used in this study the same heat treatment thus resulted in a higher DOS value for SS 304 LN1 as compared to that for SS 304 LN2.…”

“…Presence of nitrogen in austenitic SS has been reported to affect the IGSCC susceptibility to a large extent. Mozhi et al [29,61,62] have reported that presence of nitrogen to the extent of 0.16 wt.% in austenitic type 304 stainless steels increases the SCC resistance and reduces it when nitrogen level increases further. Nitrogen addition in austenitic type 304 stainless steels retards the sensitisation kinetics as for a constant carbon level, the grain boundary chromium concentration in equilibrium with the carbide increases with increasing nitrogen content.…”

“…Nitrogen addition in austenitic type 304 stainless steels retards the sensitisation kinetics as for a constant carbon level, the grain boundary chromium concentration in equilibrium with the carbide increases with increasing nitrogen content. At nitrogen levels in excess of 0.16 wt.% discontinuous chromium carbide precipitation at the grain boundaries occur resulting in grain boundary migration leading to wider (hence shallower) chromium depleted regions and enhanced sensitisation [61].…”

Low-Temperature Sensitization Behavior of Base, Heat-Affected Zone, and Weld Pool in AISI 304LN

“…Most of the studies have dealt with classic sensitization at temperatures ranging from 500°C to 800°C. [4,[12][13][14][15][16][17][18] These studies showed that nitrogen-containing stainless steels are more resistant to sensitization than their counterparts without nitrogen (such as 304/304L), within certain limitations. It has been concluded that nitrogen alloying below 0.16 pct reduces sensitization; sensitization increases, however, if N is beyond 0.16 pct.…”

Assumptions, uncertainties, and limitations in the predictive capabilities of models for sensitization in 304 stainless steels

“…In further discussing the effect of nitrogen they claimed "All these results are consistent with the metallographic data of Eckenrod and Kovack [11] which showed that nitrogen additions delayed carbide precipitation." More recently, Mozhi et al [12] and Mozhi et al [13] described work where nitrogen additions below 0.16 wt % retarded sensitization kinetics but an addition of 0.25 wt % nitrogen did not.…”